Analysing the orbit influence on multipath fading in global navigation satellite systems

For some critical static applications of Global Navigation Satellite Systems (GNSS), such as monitoring station and reference station in the GNSS control segment, multipath error shows regular fading characteristics related to satellite orbit type. However, for Geostationary Earth Orbit (GEO) satellites, observations under different systems show great diversity, the regularity of the multipath fading characteristic for GEO satellite is not apparent, and the reason is not clear as these observations can be influenced by various factors. To know the reason and the mechanism of these differences is very important for GNSS system building and monitoring, especially for the control segment, one major function of which is monitoring the whole system states and ensuring the system reliability. To explain the differences among these observations, a theoretical analysis about the satellite orbit influence on multipath fading is made in this study. The analysis is based on a proposed factor named orbit multipath fading factor, which can reflect the orbit influence independent from the uncontrolled environment factors. The analysis result shows that for GEO satellites, the multipath fading frequency varies large with time, and is very sensitive to orbit inclination, which can well explain the various fading characteristics actually observed in theory.